Generally, a cylinder deactivation apparatus, that is, a CDA apparatus is an apparatus deactivating some of all cylinders upon braking or a cruise control and stops a supply of fuel to the cylinders that is a deactivation object and an operation of intake/exhaust valves while the CDA is operated.
In the case of a multi cylinder engine such as 6 cylinders and 8 cylinders, when all combustion chambers are operated under a low load condition over a predetermined vehicle speed or an idle condition in which required power is low to generate power, extra power is generated, and therefore, by using the CDA apparatus, an operation of some of the combustion chambers is stopped (deactivated) and the rest of combustion chambers are controlled to be normally combusted, thereby promoting improvement in fuel efficiency to an optimal torque required for driving.
Fuel is not injected well in the combustion chamber stopped (deactivated) by the CDA apparatus, such that fuel consumption may be reduced, and a power loss due to a friction does not occur in the stopped cylinder, such that a considerable level of fuel efficiency may be obtained.
The CDA apparatus simultaneously opens and closes an intake valve and an exhaust valve on the basis of one cylinder. Here, when the CDA apparatus fails, the intake valve and the exhaust valve is not opened and closed but is stuck in an opened state or a closed state. In particular, when a valve fixing pin supporting the intake valve and the exhaust valve to simultaneously close the intake valve and the exhaust valve is damaged, there is a problem in that any one of the intake valve and the exhaust valve may be closed and the other thereof may be stuck in the opened state.
If the CDA apparatus fails, the normal combustion is not made in a normal driving mode, and therefore a torque variation occurs at the broken cylinder and drivability is reduced, such that the CDA apparatus needs to be quickly repaired. To this end, there is a need to quickly inform a driver that a cause of the reduction in drivability occurs due to the failure of the CDA apparatus.